New developments in plane-wave based ab initio calculations are reviewed. First, a general framework for electrostatic calculations is presented that allows 3-dimensional periodic systems (solids, liquids), 2-dimensional periodic systems (surfaces), and non-periodic systems (clusters) to be treated properly and easily (J. Chem. Phys. 110, 2810–2821 (1999) and J. Chem. Phys. 115, 3531 (2001)). Second, a general method for describing systems in which the electrons are assumed to be localized in a single small region of space embedded within a large chemically inert bath, is discussed (J. Chem. Phys. 116 5351 (2002)) that significantly enhances the ability of plane-wave based techniques to study reactions in biological systems.